1. Field of the Invention
The present invention relates to a user interface, and more particularly to a letter-recognition apparatus and method for recognizing input letters according to pen drag directions without the need for a special operation for switching a language mode in a terminal equipped with a touch screen.
2. Description of the Related Art
Conventional letter input methods in terminals using a touch screen include a soft keyboard input method and a handwriting recognition method. The soft keyboard input method typically provides an input window based upon a keyboard form that is displayed on the touch screen of the terminal. Utilizing the input window, an input operation is carried out by a pen click. The handwriting recognition method is typically a method for recognizing a person's writing, i.e. recognizing handwritten letters and converting the recognized letters using a plurality of data codes.
Terminals equipped with a touch screen include, for example, an electronic organizer, a mobile phone, a personal digital assistant (PDA), etc. These terminals are miniaturized and lightweight, and hence their touch screens are miniaturized and of reduced weight.
It is, however, necessary to display all keys for inputting letters in terminals that use the soft keyboard input method. Thus, a size of the screen necessary for inputting letters must typically be increased. As the soft keyboard for inputting letters is displayed in a larger size, the size of a display area for displaying letters that the user has selected will relatively decrease. Therefore, users who are not familiar with which letters are assigned to soft keys must view the display area to confirm that a correct selection was made of the soft keys (typically in a one by one manner), resulting in an inconvenience to the user.
Further, the risk of erroneous selection of a different key positioned next to a desired key increases when the user must click on a small-sized key of the soft keyboard displayed on the small-sized touch screen using a pen, resulting in the need for the user to input the desired key again, further inconveniencing the user. Further still, where English language and Korean language letters are inputted together (or where English language and Japanese language letters are inputted together), that is, where letters based upon at least two languages are inputted together, conventional methods require a special operation for switching a language mode when letters of one language are inputted or when letters of the other language are inputted. This drawback of a mode switching operation arises when at least two languages are inputted together.
Because the user must handwrite each individual letter when using the handwriting recognition method, an input speed is slow and the user must perform many handwriting operations. Furthermore, if a desired letter to be inputted is not written correctly, an error may occur resulting in a different letter being inappropriately inputted, which can occur frequently. In this case, because the erroneously inputted letter must be deleted and then the desired letter must be inputted again, a problem of decreased input speed and accuracy exists.
As described above, because the screen conventionally displays the soft keyboard on most of a screen area, a display area for displaying inputted letters is often of insufficient size. Further, where letters are inputted according to two or more language modes, there is a problem in that a special language mode switching operation is required. Although the special language mode switching operation is unnecessary where letters are inputted using the handwriting recognition method, this method provides a slow input speed because the user must directly handwrite the letters. Also, when a letter is erroneously handwritten, an error in which an undesired letter can be inputted can occur frequently.